Telephone system.



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TELEPHNE SYSTEM. APPLICANON FILED APR. 4. 191|.

Patented Apr. 27, 1915 a SHEETS-SHEET l.

C. SMITH.

TELEPHONE SYSTEM.

APPLICATION man APR.4.191.

Patented Apr. 27, 1915.

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TELEPHONE SYSTEM.

APPucATlpN man APR. 4. 191|.

Patented Apr. 27, 1915.

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TELEPHONE SYSTEM.

APPLICATION man APR.4.1911.

1,137,360, Patented Apr. 27, 1915.

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TELEPHONE SYSTEM.

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APPLICATION FILED APR. 4, |911. 1 ,137,360. Patented Apr. 27, 1915.

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C. SMITH.

TELEPHONE SYSTEM.

MPL10/mon mio Ara. 4. 191|.

1,137,360. Patented Apr.27,1915.

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`UNITED STATES' PATENT OFFICE.

CLAYDE SMITH, DF CLEVELND, OHIO, ASSIGNOB, BY MESNE ASSIGNMENTS, TO

*FREDERICK C. STEVENS, OF ATTICA, NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Apr. 27, 1915.

Application led April 4, 1911. Serial No. 618,926.

To all whom it may concern:

Be it known that I, CLYDE Sairrii, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification, reference being had-therein to the accompany ing drawing.

My invention relates to telephone exchange systems, and especially those of semiautomatic type as shown in application t0 J. L.-I lV i-ight, Serial No. (512,738, filel March i'.vl9,] i l y It "hi'iafor its object the improvement of -sucli systems in divers particulars.

.- 4 In order to render possible complete supervision of the mechanical,operation of the sys-tcm, I provide group lamps' for the line relays, individual lamps for: selector .and

`connector switches, including t l ieprimary' and secondary selectors, and anA individual lamp for the operators listeningr key. AIn order. to prevent a calling line from reach# ing more than onefoperator, by accident or iiiteiit, I fi-'ovide'a selflocking linelrelay, which when once energized will remain` locked 'on a vlocal circuit extending through hack contacts, on the cut-off relay, until saidv cut-ofi" relay is energized. In order that the operator may be ap'prised of tlie condition of such a line when the calling subscriber hasalrcady hungup his receiver before the operator answers, Il provide a Special tonetest in 'the primary selector circuit, which becomes operative only under the condition.

.which vit is meant to indicate. As an improvement in the means for releasing the circuit between subscribers, I provide Specialv means on the key set distributingswitch.

.which determines the order and destination of the current impiilscs' from the Sending machine,` said means becoming operative. after one complete c 'vcle of operation of the sending uiachine andthe switch. to Vclose the release circuit switch.

My invention is illustrated in the acconiianviiilr drawimrs. showinr acom ilete svsi f F* l 4 I* .l

teni embodying the saine, and the principal nected to corresponding contacts, that is t0 in all the .first selectors. A, .11g

pieces of apparatus, used therein.

l detail in Figs. 2 to 6 inclusive.

At the right Y Fig. 2isa diagram showing the subscribers line Aand the primary control circuits at the central office. Fig. 2* is a modification of` the kickof'f switch control. Fig. 3 isfa diagram showing the primary and first selector vSwitch circuits. Fig. 4 is a diagram shoivit/ xg the connector switch circuit. Fig. 5 is'ia diagram showing the operators trunk with key-set control circuit. Fig. G is a diagram showing the operators key-set and sending machine circuit. Fig. T is a diagram showing a party line circuit accessible from the connector of Fig. 4. Fig. S is a diagram showing a detail of secondary call distribution for simultaneous calls.

In this description I will first outline the s vstcm as shown in F-ig. 1` and then take up the circuits in Figs. 2 to G inclusive, and explain -their operation in detail.

Ind Fig. 1, each element is marked with thetitle by which in general it will be designated throughout the case, and enough of the reference letters and numerals aieshown' originate at the left hand endor station, and

all connections to progress toward the right,

sinned as the right hand subscriber. in every there is no such limitation in practice, but

the wanted or called subscriber being asthis assumption simplifies description and illustration. ln this figure therefore three :laibscribcrs'are shown at the lefthand end of the sheetwhose lines terminate on multiple contacts of vthree primary selector switches,

alsv

cach of'which has a pii'oted wiper or contact which canv be swept over the line contacts to connect with anyone of them. Each of these wipers forms one terminal of a first selector truuk, the other terminal of `which is asimilar wiper in the first-Selector'switch. 'lhe fixed contacts over which these wipers .sweep iii all the switches are usually referred to as bank contacts. and, in mass as contact banks." The bank contacts'bf the first selector 'switches form thetermina'ls o f second selector trunks, each of which is con` say multipled" IT', d ends the second selector scribe-.r9 stations. comici-todito it in parallel.

These are party lines, so shown for the purp .se of illustrating the principle of selective ringing. which forms a part of the system. They need not all be party lines however, nor is it necessary that the subscribers shown on the right of' Fig. l should be different from thosel'iown at the left. On the contrary, ercry subscribens line, in order to have complete service, must be connected to terminals in both the primary selector switches and the connector switches, since it is through the former that the subscriber when calling reaches the central office, and it is through the connector switches that the central oflice when calling reaches the sub- Y scrihcr. The connections of a line to primary and connector switches are made in parallel, )ustas are those of cach line tothe several switches of either class. Associated soA with each conn ctor switch is an auxiliary or ringing selector switch. The wiper of this switch sweeps over contacts connected to several ringing generator'sfeach of which generates a particular distinctive character of current. At the 'several stations on a party line the bells are designed and adjusted so as to respond selectively-and exclusively, each t-o its ,own particular kind of current; only. At thc last stage in a connection, when the wanted s'ubscribers line has been `picked out by the connector switch, andthe ringing selector has been set so as to bring into service the proper generator, the wiper of thatswitch is' then automatically connected through the connector to the subsc ribers line lto ring the bell. A At all other times the ringing selectorremains disconnected.- v

f,'lheprimary `selector switches are controlled by the subscribersin calling, throuvh the medium of line relays at thecentral o ce which respond to the flow of current in the subscribersl lines, and Awhich when so-enerswitch. The t pe of lswitch employed `in this' System ise -means of current impulses 0f :predetermine d gig/,edguide and direct the primary switch wipers to their respective line contacts. 'AA

corresponding to the ectromagnetically4 driven by number sent in predetermined groups, which incre the switch wipers step by step over the bank contacts. These impulses are supplied, and the switches are controlled, by operators at the purpose are given access through secondary selector' switches to the first selector trunks, hereby they arc enabled both to receive their orders from the calling subscribers, by way of the primary selectors, and to send impulses to the first selector and Succeeding switches, for the purpose'of making the desire-d connect-ion. The secondary selector switches as will presently be seen, are initially responsive to the subscribers acts in calling. In lfact, broadly speaking, their operation is the same as that of the primary selectors, the flow of current in a calling subscribers line and in the first selector trunk connected thereto causing a secondary selectorswitch wiper to be guided and directed automatically to a contact in its bank which is connected to the first selector trunk in question.

In order to select and transmit the propel' impulses for line selection I provide .eacl'i central oilicc, who for that 7 operator with a key-set mounted on a suitable desk, and having associated with it certain signals which guide the operator inthe performance of her duties. The key-set in general appearance and arrangement is quite similar to the key board of an adding ma- .lng the signal, the operator asks the subscriber for 'the number wanted, and proceeds to depress the correspondings keys or i buttons. She then presses a separate st-arting key, and groups of impulses, correspond` ing to the buttonsdepressed, will thereupon be transmitted tlirou'gh the key-set, through the secondary selector switch, and through" the first selector trunk to the first selector switch, causing the following operations: (l)

the first selector switch is stepped around to the contact of a second selector trunk leading' i to a. second selector switch in the thousands group corresponding to the first digit set up; (2) the second selector switch is stepped around to select a connector trunk. leading to a Vconnector switch of the hundreds group second digit' set up, (this particular connectorcontaining,terminalsof the line wanted) (i3 and 4) the connector switch is then stepped around in respouse tothe'third and impulses to pick out the terminals ofthe lino wanted and (5) the associatedl ringing fourth groups of v selector having been set in response to the operation of the impulses, the wanted subscribers bell is autonnitically rung.

Reference has oeen made above to thousands groups and hundreds groups of circuits. This particular switching system is known as a percentage trunlcing system. That is to say, the connection between any two lines is effected by successive steps or successive acts of subdivision. For example, in an exchange serving ten thousand subscribers, the second selector switches would be divided into ten groups, through one of which access could be had to the connectors containing lines numbered 'from 1000 to 1999, through the next to lines numbered from 2000 to 2999, and so on. Similarly, the connector switches in each thousands group .would be divided into ten sub-groups accordn 'ing to their hundreds digit. Through the first of these sub-groups, lines numbered from to 199 could be reached, through the second lines numbered from 200 to 299, and so on. Obviously therefore, access could he had to any desired line by selecting first a second selector of the thousands group in which that line number occurs, and then by ieans of that selector picking out aconner-tor of the hundreds group in which the line number occurred. That connector would then actually contain terminals of the wanted line. Of course in practice the wiring between the different groups of switches is quite complicated because of the large number of trunk wires employed to furnish the various combinations required between the switches, but the theory is quite simple, and is well enough illustrated in Fig. 1. As soon :is-one of the subscribers at the left of Fig. l has become connected in the manner stated with one of the subscribers at the right, it is unnecessary and in fact undesirable for the operator to remain longer lin cormcetion with them, and means are provided for automatically cuting ofi' and restoring the. secondary selector switch as soon as this condition is brought about. Thereafter all the switches in use between the two subscribers are under their own control, and when they finally hang up their receivers the several switches are automatically restored, the connection is broken, and all parts resume the positions of idleness diagraphically illustrated in Fig. 1.

lt will be noted after reading the fore.- going, that portions of. the apparatus and circuits at the central office are common to all or a number of subscribers lines whereby confusion might arise from simultaneous connection of more than one line to the saine trunk, more than one trunk to the same line, more than one trunl to the same operator. or more than one operator to the saine trunk. Special provision is made however, to prevent this.v At the left of Fig. 1

l have indicated what I call a primary distributing switch and a secondary distributing switch. The first of these contains in its banks testing terminals of the primary switches or first selector trunks. It is actuated in response to the subscribers calls, and always acts to select and start up an idle switch and trunk for connection with the calling line. There is only one distributing switch for all the primary selector switches serving the same group of subscribers` hence only one switch can be started at a time, and this prevents more than one trunk being connected to the same line. In going to the line, the action of the primary switch is to test over its banlrY contacts until it rca ches a contact which has had its condition changed, due to current flowing in the calling line. If more than one line is calling. the switch will stop at the first one to be reached, and thereafter the distributing switch will start another primary selector to search for the second calling line, whereby it is impossible for more than one line to get on the same trunk. The secondary distributing switch performs the same functions with respect to the operators or secondary selector switches, and is actuated also in response to the subscribers calls, so as to start only one secondary selector switch at a time for any one group of trunks.

As no claims will be made herein to the mechanical features of the apparatus employed, detailed description-thereof is unnecessary: and the construction and functioning of the several pieces will be sufficiently understood from the detailed statement of operation hereinafter, read in connection withY the following remarks: The unit of the connective system is a one hun dred point switch, of the saine type as that shown in Letters VPatent No. 977.536. granted December (l. 15H0. to Charles fl'. North. The primary and secondary selector switches shown in diagram in Figs. il and 5 require a row test wiper on the spindle in addition to those shown in the North patent, but this may be afhxed to the spindle in any suitable way, being of course insulated therefrom. The function of this wiper as it is shown at m2 and w82 in Figs. 3 ai d 5 respectively, is to pick out the row of colitacts in which thi` individual contacts of a calling line or trunk may be found. This is done during the first or rotary motion of the spindle, and when the busy or callingr row-contact is found, the switch stops rotating and starts to step up the row designated. tactS y11725, 'w53 and y11:"2, iti-Figs. 3 and 5 respectively, then slide up the row of individual test contacts until the particular calling Contact is reached, when all motion ceases. andas the connective or talking contacts 1/:--w, 't .8--l,/*"1 (Figs. il and 5; more constantly with the test wipers and are alined The lower or test conv fl t) loi.)

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roup has its first contact s2 wired to num- Rer two row contact of the first secondary switch S2.y its second contact s2" wired to number two row contact of the second secondary switch S2, and so on.

ln an exchange of one thousand lines the contactI s2 of the tenth switch S2 are Wired t0 number ten row contacts of the secondary switches S11. If in an exchange of one thousand lines simultaneous calls should come in from each group of one hundred lines and ten secondary selector switches S were provided, one row contact in each switch S1 would be made active. lithout any confusion each' switch S8 would test for its active row contact and then find the individual contact in the row. 'l`he individual test contacts would he Inultipled in a group of secondary switches SS so that any switch SB in the group can pick out any trunk belonging to its group. The relay R1 has one terminal of its winding connected to the lwiper arm ws of the switch S. When the arm w3 in rotating finds an idle primary switch S* the relay R1 is energized in series with the relay R12 (Fig. 3) and opens the circuit of stepping magnet Mft'lrus bringing the switch S to rest. The energizing of the relay R7' causes the switch S2 to immediately start to pick out an idle secondary switch S2. The switch S4 can be testing for the calling line While the switch S2 is testing for the trunk shown in Fi 3. The relay R13 acts somewhat as the line relay R', connecting battery to its individual tests contacts in the switches S2.

lt will be noticed in the statement of operation hereinafter that the relay R13 is not dcenergized until the primary switch finds the calling line and the secondary switch S8 finds the trunk connected to that line. By this arrangement all confusion is avoided regardless of which switch performs its functions first.

Referring to Fig. 3, the relay R12 is the row test relay, and is energized when the wiper w22 finds an active contact, disconnects rotary relay R18 andf in its place connects vertical relay R19. The relay R15 is used in testing for the individual contact as well as a battery supply relay for the calling subscriber. Then energized this relay disconnectsI the row relay R12. The deenergizing of relay R12 disconnects the relay R117 from the test wiper w25 and connects it to the sleeve wiper 1114, in series with the cut-ofil relay R2. Relay R14 is the tip battery supply relay and controls the release magnets M3 and MA1 after the first selector switch S15 has moved off-normal. T he relay R42 is used for opening the talking circuit While theA impulses are being sent to operate the outgoing switches. This relay also with R111 jointly controls the relay R12. Relay R1 is the test relay having its locking Contact '1412' connected to the test wiper w1". Its circuit is initially closed through the contacts of relay R42 and foot springs 144 and 145. After the switch S5 makes its first vertical step the circuit of this relay is maintained through contacts of relay R12 and test wiper w147 so long as this wiper encounters busy contacts, which are grounded through other switches.

Referring now. to Fig. l, relays R22 and R22 respond to impulses from the sending machine. Relay R22 receives the first set of impulses belonging to the connector and causes the stepping magnet M11 of the switch S7 to step around so as to pick out generator current of the proper character. Operation of relay R22 closes the circuit of relay R2* whose locking contact 'V221 is con nected to the bottom contact of relay R22. Relay R23 also closes circuit of relay R27. This latter remains energized until the called party answers or until the alling party hangs up his receiver. In case the called-for line is busy, relayr R27 Awill be deenergized by action of test relay R21. lays R2", R27 and R2 all have their circuits completed to ground side of battery through test wire 200, contacts C22", w1, 14T, vrff" to ground. Vr'hen the calling party hangs up his receiver after failing to get his party, switches Si and S5 are restored and ground removed from test wire, causing dccncrgiza tion of any of the relays R22, R27 or R2*1 which happen to be locked. The switch S7 is restored to normal after the called suhscriber hangs up his receiver or when the relays R25, R27 and R22 are deiinergized; and just before it reaches its normal position the wiper arm w87 passes over a contact and closes the circuit of the release magnet M12 restoring the connector switch S to normal position. Thus the connector switch S has a quick release if the called-for line il busy, and after the called party answers a slow release by switch S7 which takes care of any accidental shaking of the receiver hook when the called partv answers.

Referring to Fig. o relay R21 is the row test relay and R2" the individual test relay. Relay R32 is the control relay and corre sponds to relay R13 (Fig. il). Relay R"gli is the signal relay and pulls up in series with relay R12 (Fig. i3) after the primary trunk has found the line and the secondary switch Ss has found the trunk. this relay closes the circuits of the signal lamp L7 (Fig. G), the guard lamp L2 and the night alarm bell. Relay R22 is the listening relay actuated by listening key LK. Operation of this relay denergizes relays R32 and R12 and closes circuit of listening lamp L". Relay nl is the starting relay and is energized in series with R42 by the key SK. This relay disconnects relay R23 and connects the starting cam on the send- Thc operation of 'l rullini-Q um mik dam*

:wim Hmmm 1 MMU um.

will@ HE' hz this uw it would requiie three more steps for Wiper les to complete the circuit of relay RG. It wiper leal is resting on multipled contact 181" when relay R9 is energizetfl, it will require'only three steps of wiper les before the circuit of the relay R is closed. Then relay R operates it places ground on Q18, 219, rm. 31, M to battery, operating magnet M to s tep uiper trs to the next contact and thereby unlock the relay R whichV in turn denergizes relays R, R*l and R8. The operation of relay R also places ,ground on 318, Q20, w82, 221, rfi (Fig. 5), 122, 171, throurh release magnet M1 to battery. causing tbe release of secondary switch Sh lf for any reason the Secondary switch, after it is selected fails to make proper connection with the trunk in Fig. 3 so as to relieve relays R13 and R5, the kicleotl switeli will come into play and between three and sii; rotations of the sendingr machine cause second ary switch Ss to be released and the switch 5l to pick out another trunk.

Operation: The subscriber at station A desiring a connection lifts receiver R -from hook H which bridges his telephone ari-oss line Wires 1--Q, energizing relays R1 and R3 by Way of B, 19, 20, R, 21, R', 1, station A, 2, T22, 23, ground to battery. Re lay R locks to ground through 1*, 224, and r2, and connects ground to individual test Contact cf-5 through 25 and 1', While R3 connects ground to row test Contact 026 through 2G and 1"1 and completes circuit of group lamp L and relay Rt,r the former from B, 19, 27, L, 28, r3?, ground to battery, the latter from R, 19, Q9, R4, 39, rm', to Vground. Lamp L lights, and Arelay R4 completes eireuit of stepping magnet M to interrupter l for intermittent ei'iergization over the path, B, 19, M, 31, 1*, 3:2, ""9, il?. l, to ground. Magnet M mores switch 'S step by step until wiper irs engages a contact a connected to relay R13 (Fig. 3) of an idle primary selector trunk, whereupon relays Ri and R13, (Figs. Q and are energized by current through B, (Fig. fl), 3l, 35, 36, rl, 37, R13, 38, (38 Fig. Q), s, ws, 39, R5, 49, 742, to lgfround. Relay R5 opens circuit of magnet M at rs1, locks itself to ground through 752 and completes circuit of R over path B, 19,

41, R11, 4Q, w53 and ground. Relay R13 locks itself to battery through rm, 43, T421, 44, and 34 to Il; connects battery to one terminal of relay R12, through 34, 35, rw, l5, 4G, rm,

.47, and 48; and also completes circuit of rotary relay R18 through 'rm and interruptor' I, so that this relay is energized intermittently, its circuit being: B, 34, 35, frm, 45, 46, 1m, 47, 4.9, 50, R18, 51, w21, 52, w32, i to ground. At each actuation of relay R1g magnet M5 is erfegized by current trom B, 34, 57. contracts 58 of foot step switch F1, 59, M", 53,7'181, ground, stepping primary selector switch S* around until Wiper wze engages rou' test contact (x26 whereupon relay R12 is energized over circuit B (Fig. 3) 34, w33, 45, 4G, w52, 1.7, 4s, R12, 49, wf, 0f, (Fi 2) 26, rm, ground to battery. Relay RE locks itself to ground through T122, connects test wiper L02" 'to sleeve relay R" through 54, rm and 55, and shifts interrupter l from rl'itary relay R18 to Vertical relay RH at rl, so that Rl" is intermittently ene*L i d over the cireuit: li, 3l. Si, rm, i5, i6, 1", 47, 49,1t, Sil, rm, 59 rm, l, ground, to battery. t earn aetuation of relay R19 Vertical magnet lll is energized over the path ll, 34, G0, M, (3l, 7" to ground, steppingsr'iteh S4 up until Wiper w25 engages individual test eontaet @'25 (Fig. Q) Where0 upon sleeve relay RV is energized over the maar B. (Fig. a), ai, a5. R15, sa', frm, 54, w25, c25, (Fig. 2), 25, 7""'2 (of relay R), ground to battery. Relay R15 connects battory to trunk conductor 7, by way of 7551, (33, (il, 7^, (i5, and resistance 7', and at the saule time opens the circuit ot' relay R12 at rm. Relay R opens circuit of vertical relay R1D and magnet lllC is delncrgized, which permits wiper y2/7-'5 to stop on Contact c25, wipers 103 and. as" engaging contacts f3 and c. resIwctirely. Tip relay RM is non? en` ergized through subseribens telephone in ries with R15. Simultaneously with the selection of the Calling line described. dis tributing switch S2. (Fig. 2) is .stepped around in Search ot an idle secondary selee-- tor, by magnet M2 in circuit: B. 19, 41, 66, (i7, G8. rm, G9. M2, 70, rl, 71, I to ground. Switch S2 continues to step around until 1wiper arm uw i engages a Contact S20" con netted to an idle secondary selector, whereupon relays R and R3, (Figs. 2 and 5) are energized in series. the eirouit being: l'i, (Fig. 8P, sprinfs 'T3-m74 of operators jack J, 75, syn-ings m-77 of foot sliep switeh lf", 7S, R32, 79, through Fig. 3 into Fig. 2, afm, 103W', 80, 81, Rl, S2, rm to ground. The actuation of relay R10 causes the eri-- ergization of relay R9, the circuit being: B. 1a, 41, ae. e7, w01, e3. ai, n?, sa, we t@ Iground. Relay R9 locks itself to battery through w92, and opens ci` :uit of magnet M2 at r'J-, whereupon switch S2 comes lto rest with wiper arms 11i-s2. wam, and 'wem resting on contacts s2, 3'1", and am, respectively.

The attraction of armatiu-e n ot relay R connects battery to wire 99 which completes part of the row test circuit and the attraction of armature 1""3 completes the circuit ot relay R8 as follows: B, to R8, 2523. rss to ground. Relay R8, grounds wire 8G, shunt ing relay R10 out of series with relay R3E (Fig. 5) the circuit of the latter vrelay now going direct to ground by way of Wire and armature r. Relay R32 (Fig. 5) com pletes the circuit of rotary relay Rm through interrupter I so that said relay is intermittently energized by current over B, 86, 87,11*,

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contacta' sfontainiin;l \n,=r:1ei",-i hin" is a1; lhlf'. t rotary z-tep ol' :switrh rontarf il lf are cloned, completing th olinorniah7 lanu. lj) through i, nti, ll l. l), 1.195.105, liti, i to ground; alan ieutallj.' 'during the release circuit through :mannen Ni and M4, hereinafter desrrihe-l. livr the nunihor Canis have paw-1l under' ilu-ir i-es pe|ftiie springl Cain 1)" again @lof-rs ir Contact?l di* stepping sr-:itrh b" around to hringf` its wipers into engigjrinrnr uhh the next Set olA contacts. Winer arm: uur and /r-r""" olI switch H" noa momie their respertiie rontaethV 2s",

and L "L and an U12 (Fig. (i) ennnelftfs lest nupnhfe, nuire lili) through springs JW, eondurtor lim and springa d to ground during ien rloanrw of" #wings nl", whereupon rertieal relay ll (Fi Il) interniittontly energgixwl lhroui'h: `und, (/l. lilo, ,"Y, llfl, rias ing. 5j, ma 1,135. (135 Fig. it). r

wond ronv oi roi ureetor named who v No. hattei'y, to ground.

Relay R2 internilttentljf olosrs Circuit of magnet MT at stepping up wipers we 111'" und furl of' the tint selector Switoh Si to engage eon'art nl, c :ind ""0, res er (,v" tively, leading to a connector trunk (Fig. 4). At the l'irwt, re-,rtieal movement 'of the spinde oi Snitch r" the circuit of relay R is oprneol a1; connat springs 144 and 145 of Switch l. and ahoullil the connector trunk (Fig. 4') hr huirheeauso of the wipers of another first selector switch resting on the multiples ol' cont-.irte 02", rela)7 R would remain'energized through B (Fig. 3), 34. 44, rm, 142, It, M6, 7141, 147, w1, om (Fig. 4) to the multiples o'l' uw and thence through the rirfuit of thi other lirit selector hy nay of itzav wiper wim (as in Fig. 3), 147, rm. ground. to hattet-y.

The armature rm of relay It, remaining altrarted permitir. the 'next tost impulse to energize vertieal relay lig ,stepping the wipers up to the nml ,sei o' eontaels, and ,so on until an idle ronnert if rf-af'hed. alien, rela)v R heing' deprived of ground, ieleases ita4 armatures.. fm. diseonnects iniconvertor trunk 'wregy g'fl() and l are nov. ronnerrted to the tip anff leone fou|111rto|ial and lo through armatures il and 1*1': respectively, und Contact 02"" (Fig. and its multiples are con neen-d to ground through: wm, (Fig. 3), ll?, und rm. After cam D12 (Fig. has passed :pringa rl, starting anni D again closes springs f/l, steps ai. iteh S3 around to hrinn; ita wiper into engagement with the third t of contara, Wiper arms Ira-1, mail" and ausw" non' 1if,.1gr, contacts 3s", 35"" and 3am", respectively. The number CamaV now pass under their reapeetiro eontact Springs for the third time and send impulses. correaponding: in nuinher to the desired ringing ,fn-nerator (in liis ease Xo. f5), to relayv H21* t Fig. 1), through: ground, springs fr" (Fig.

in, um, un. am 197, (197 Fig. s 1,

en, mi, 1:51, mi, 130, (1:i'0`I1g. 3), T411, 133, i1, Q09, 013, (rig. 4), 16, w, 201i, R23, 205,

l to ground. Each artuation of relay R2 energizes magnet M of switch 57, th rough n, zoo, s, 20u, 210 and 211, 212, 21:3, M, 2H, :215, 1'2"" to ground. Magnot MIl moves switch S7 forward three steps, bringingr wiperb uns?, ws?" and www' onto contacts 2587, 3H?" and ism respectively.

The tiret actuation ot' R2 energizes l11 and E, the first through: l5, Q06, '207, i305,

Zl?, R2, 202, 200, 02", 1014"', (Fig. 141', 1"3 to ground. lor-king' itselfA to battery through 240, r2. i250, rm, 20T; the second rela \r through: l), 1 (ol' relay hw), 23 22N), lm, 2335, 7'2", 2916, 203. to ground` locking itwlf to batti-1)' through: 231:2, 15"", 2325, rm, 231. lam D (Fig. again closing contacts d mores switch s3 one step bringing its wip r5 onto the Fourth set of eontaets. 'iper insg" nonv engages rontart hrm and the nuinher calm` closey their respeetire Springs and send iinpulnos to R22 (Fig. 4) through: ground., rontaetn (il, (Fig. (3*) 190, (I4, 225, 2211, 22", if at Strip K2, mi, (224 rig. .1), flsi", usf", 132, fw, s, 135, (ll Fig. l `r'm, 134, l0, zal", (Fig il 15, f

rf, 2251, 22e, 23;, 1, 3, w1, ern, baan-y to ground. Each actuation of Il onta-fixes niagrnet M" through: B, Q06, QOH, 23T, :236, 23E). M, 240,1'2, rground. Magnet M moro@l Switch S6 forward four stops bringingr wipers fw and In onto the fourth row of eonaetn, in whieh lie tho wanted line eontarts.

The lirst actuation of l opens the locking;l circuit oi3 R2" at frm. The first rotary step opens springs 2l0-2ll and Clones Zlib-421V. whif'h shifts battery lead'20!! `l'roin Ml1 to Mm and lights lamp L6 hy current through: l, 2id, 246, 245, i264, 266, rm, 248, L to L'round. (Iam l)11 (Fig. 6) again closes contaets d and ,senda one impulse over wire ll, artuatingy switr-h S3 to step its wipers onto their fifth Set of rontaets. After nain lll has passed contacts r, the number Canis again aetuate their respeutire spring oontart4 Ywinding.;r unit impulses through 2471. lill (lf'ig. 5), wiper uur, 5.6, to R23 (Fig. l).

Each actuation of relay R23 energize M1",

Wiper arm w87 engages contact 987 (which occurs just before the switch reaches its normal i'iosition) the circuit of release maffnet M is completed as follows: battery zuil, 20T, i if?, ics?, De", 290, 269, MV", ground, to battery. 'iiie connector switch S then returns to its normal position.

ilaiing thus desI` :ribed my iiii'entionvlint l claim and desire to secure bv Letters Patent is:

l. ln a tcleplnnic exchange s stem, a plui-ality oi' line circuits, switching apparatus l'or etl'ecling interconnection thereof, an operaions circuit, intens l'or eli'ecting an initial. connection olI a line nhen calling to said operatori, circuit, an operators telephone, ineaiis to connect the same with the operators circuit after said initial connection, and a signal dei ice actuated only when' the operatoi"s telephone is so connected.

ln a telephone exchange system, a plurality of line circuits, switching apparatus for interconnecting the saine, an operatoi"s circuit, iin-,uns for ci'leetinlg:r the initial connection oi' a line when calling to said operators` circuit. a, called signal associated with the operators circuit and adapted to be displayed to indicate the call, an operators telephone, means to connect said telephone to the operators circuit in response to the call, and a supplemental signal associated with said connecting means and adapted to be displayed only when the telephone is so connected.

23. .In a telephone exchange system, a plu rality of line circuits, switching apparatus for interconnecting them, an operators equipment circuit, automatic means for efl'ecting the initial connection of said circuit with a line when calling; a signal associated with sani circuit and adapted to be autonialicallifY displayed when it is so connected, an operators telephone, means for connecting tli saine to the opcrati'irs circuit, and a supplemental signal device adapted to be automatically displayed when the telephone becomes so connected.

4l. ln a telephone exchange system, a plurality of iine circuits, switching apparatus for interconnecting the saine, and operators equipment circuit, automatic means for effecting an initiai connection of said circuit with a line when calling, a relai/adapted to become energized upon the completion of said connection, a called signal device controlled by said relay, an opcrators telephone normally disconnected Vlroin said circuit, means tor connecting the telephone in response to the indication of the signaling device. and a supplen'iental lsignal device conlrolliiil in the actuation of said connecting means.

(i. la a telephone exchange sistem, a plu-- ialtif .line .tiri-nits, automatic switching apparatus for interconnecting the saine, in operators circuit, means for eileetingg; initial connection oi' said operatore vii with a line when calling'. an inicratosf` phone, means ior coiiiieetne; sana operators circuit in respons nection from said operaio. automatic switching' appui means for said switching; a p ed le he controlled throng/,h ai circuit, a signal diniciadapted ti i inaticallg1 displayed when thc said tele; bccoi'nes connectciii with the operato cuit, and a second signal der f displayed upon the initial operation of :san switch actuating means.

G. ln a telephone exchange system, a nlurality of line circuits, automatic swiii apparatus for interi:onnecting iiic L operators circuit, automatic means for ci! itecting initial connection oi' said fja'ieralors circuit with a line when calling and with said automatic switching apparatus, an operators telephone, ineens for connectingfA the same to said operators circuit, a signal device becoming aiuoinatically disnliivcil when the telephone so connette.v a selective controlling device for the aniomatic switching' apiliaratns, starting inea therefor, means for connecting the saine to the operator-s circuit and thence to the anto-- matic switching apparatus, and a signal device becoming displayed in the operation of the starting means.

7. In a telephone Xchange s if'sten'i, ii rality of line circuits, automatic "riil for interconnecting the saine, an oit circuit, automatic means for eiiecting ir .tial connection of said operations circuit n iti a line when calling and with the aiiton'iatic switches, an operators telepln'ine a ils key, a lamp signal controlled by i i ing key, an impulse sending deine switches, a starting button therefor, und a second signal device controlled by said starting button.

8. In a telephone exchange system` a afinrality ol' line circuits, automatic switifliingf apparatus for intereonnecting the saine, an operatoifs circuit, means i'or effecting initial connection of said circuit with a line when calling and with the automatic itiiliini; appa atus, e call signal associated with the opcraters circuit and becoming displayed on the completion of said initial coniicction, an

operators telephone, means for connecting,

the saine with said circuit in response to a all. a second signal device becoming displayed on said connection of theI telephone, a .selective controlling device for the antol niaric switching apparatus. starting aiiwns ilierel'or und a third .signal devi-fc i inning displii'i'r-il on the actuation of said startmi means. wlwiliy the progress ol an oni-iva Si o iiiifj 

